Muteins of various lipocalins are a rapidly expanding class of therapeutics. Indeed, lipocalin muteins can be constructed to exhibit a high affinity and specificity against a target that is different than a natural ligand of wild type lipocalins (e.g., WO 99/16873, WO 00/75308, WO 03/029463, WO 03/029471 and WO 05/19256). In particular, international patent application PCT/EP2011/070119 disclosed lipocalin muteins, derived from human lipocalin 2 (or hNGAL), which are capable of binding Glypican-3 (GPC-3).
Glypican-3 (GPC-3), whose expression has been implicated in many cancers, belongs to the glypican family of glycosyl-phosphatidylinositol-anchored heparin sulfate proteoglycans. (Sasisekharan et al., Nature Reviews I Cancer, Volume 2 (2002).) GPC3 is considered an oncofetal antigen, because its mRNA and protein expression is increased in, including without limitation, hepatocellular carcinomas (“HOC”) (Sung, Y. K., S. Y. Hwang, M. K. Park, M. Farooq, I. S. Han, H. I. Bae, J. C. Kim, and M. Kim. 2003. Glypican-3 is overexpressed in human hepatocellular carcinoma. Cancer Sci 94:259; Hsu, H. C, W. Cheng, and P. L. Lai. 1997. Cloning and expression of a developmentally regulated transcript MXR7 in hepatocellular carcinoma: biological significance and temporospatial distribution. Cancer Res 57:5179; Zhu, Z. W., H. Friess, L. Wang, M. Abou-Shady, A. Zimmermann, A. D. Lander, M. Korc, J. Kleeff, and M. W. Buchler. 2001. Enhanced glypican-3 expression differentiates the majority of hepatocellular carcinomas from benign hepatic disorders. Gut 48:558.), colorectal malignancies (Lage, H., M. Dietel, G. Froschle, and A. Reymann. 1998. Expression of the novel mitoxantrone resistance associated gene MXR7 in colorectal malignancies, Int J CHn Pharmacol Ther 36:58.), prostate cancer cells (WO07/081790), embryonal tumors (Saikali, Z., and D. Sinnett. 2000. Expression of glypican 3 (GPC3) in embryonal tumors, Int J Cancer 89:418.), melanoma and melanocyte nevus (Nakatsura, T. F T. Kageshita, S. Ito, K. Wakamatsu, M. Monji, Y. Ikuta, S. Senju, T. Ono, and Y. Nishimura. 2004. Identification of glypican-3 as a novel tumor marker for melanoma. Clin Cancer Res 10:6612.), Wilm's tumor, hepatoblastoma (Jakubovic and Jothy; Ex. Mol. Path. 82:184-189 (2007); Nakatsura and Nishimura, Biodrugs 19(2):71-77 (2005)), lung squamous cell carcinoma, neuroblastoma and testicular germ-cell tumors, as compared to normal tissue where GPC-3 is usually down-regulated or silenced.
It would still be desirable, therefore, to have alternative lipocalin muteins that are capable of binding GPC3 but are derived from a different wild type lipocalin (SWISS-PROT Data Bank Accession Number P31025), human tear lipocalin (TLPC or Tlc, also termed lipocalin-1, tear pre-albumin or von Ebner gland protein), and can be used in pharmaceutical and/or diagnostic applications. Accordingly, it is an object of the present disclosure to provide such tear lipocalin muteins. No such tear lipocalin muteins having these features attendant to the uses provided by present disclosure have been previously described.
Based on the discovery of GPC-3-binding hNGAL muteins that can be internalized from GPC-3-expressing cells' surface, and therefore, are capable of delivering one or more therapeutic moieties or one or more detectable labels to cancer cells expressing GPC-3, the present disclosure provides a promising way, using such hNGAL muteins, for targeted delivery one or more therapeutic moieties or one or more detectable labels to cancer cells expressing GPC-3, hereby enhancing the antitumor activity of the therapeutic moieties and reducing the systemic toxicity of the therapeutic moieties and detectable labels. No such uses of hNGAL muteins having these features attendant to the uses provided by present disclosure have been previously described.
The recitation of any reference in this application is not an admission that the reference is prior art to this application.